fix: multi lang button label issue (#7117)

apps/web/app/lib/survey-block-builder.test.ts

@@ -0,0 +1,80 @@
+import type { TFunction } from "i18next";
+import { describe, expect, test, vi } from "vitest";
+import { TSurveyElementTypeEnum } from "@formbricks/types/surveys/elements";
+import { createI18nString } from "@/lib/i18n/utils";
+import { buildBlock } from "./survey-block-builder";
+
+const mockT = vi.fn((key: string) => {
+  const translations: Record<string, string> = {
+    "common.next": "Next",
+    "common.back": "Back",
+    "": "",
+  };
+  return translations[key] || key;
+}) as unknown as TFunction;
+
+describe("survey-block-builder", () => {
+  describe("buildBlock", () => {
+    const mockElements = [
+      {
+        id: "element-1",
+        type: TSurveyElementTypeEnum.OpenText,
+        headline: createI18nString("Test Question", []),
+        required: false,
+        inputType: "text",
+        longAnswer: false,
+        charLimit: { enabled: false },
+      },
+    ];
+
+    test("should use getDefaultButtonLabel when buttonLabel is provided", () => {
+      const result = buildBlock({
+        name: "Test Block",
+        elements: mockElements,
+        buttonLabel: "Custom Next",
+        t: mockT,
+      });
+
+      expect(result.buttonLabel).toEqual({
+        default: "Custom Next",
+      });
+    });
+
+    test("should use createI18nString with empty translation when buttonLabel is not provided", () => {
+      const result = buildBlock({
+        name: "Test Block",
+        elements: mockElements,
+        t: mockT,
+      });
+
+      expect(result.buttonLabel).toEqual({
+        default: "",
+      });
+    });
+
+    test("should use getDefaultBackButtonLabel when backButtonLabel is provided", () => {
+      const result = buildBlock({
+        name: "Test Block",
+        elements: mockElements,
+        backButtonLabel: "Custom Back",
+        t: mockT,
+      });
+
+      expect(result.backButtonLabel).toEqual({
+        default: "Custom Back",
+      });
+    });
+
+    test("should use createI18nString with empty translation when backButtonLabel is not provided", () => {
+      const result = buildBlock({
+        name: "Test Block",
+        elements: mockElements,
+        t: mockT,
+      });
+
+      expect(result.backButtonLabel).toEqual({
+        default: "",
+      });
+    });
+  });
+});

apps/web/app/lib/survey-block-builder.ts

@@ -302,7 +302,9 @@ export const buildBlock = ({
     elements,
     logic,
     logicFallback,
-    buttonLabel: buttonLabel ? getDefaultButtonLabel(buttonLabel, t) : undefined,
-    backButtonLabel: backButtonLabel ? getDefaultBackButtonLabel(backButtonLabel, t) : undefined,
+    buttonLabel: buttonLabel ? getDefaultButtonLabel(buttonLabel, t) : createI18nString(t(""), []),
+    backButtonLabel: backButtonLabel
+      ? getDefaultBackButtonLabel(backButtonLabel, t)
+      : createI18nString(t(""), []),
   };
 };